What is required of me after I made a vow to stop masturbating, in exchange for fasting six or nine days for each instance, given that I have forgotten the exact number and sequence of days? Does the vow include thoughts or glances, which were not my intention when I made the vow? And what should I do if I am unable to fast due to a legitimate excuse?

We ask Allah to accept your repentance. This vow is a vow of obstinacy (nadhir lajaj), and you have the choice between fulfilling what you vowed or performing an expiation for an oath (kaffarat yamin (definition)).

If a word implying repetition was used, the expiation is repeated. If no word implying repetition was uttered, then only one expiation is required.

According to the Hanbalis, only one expiation is required if you have not yet expiated for any of the vows, due to their intermingling. Acting upon this opinion will suffice you.

If you wish to fulfill the vow, you must fast for six days only, not nine, and consecutive fasting is not required unless you stipulated it.

Menstruation and illness do not break the continuity of obligatory consecutive fasting, but fasting is not required to be consecutive unless it was intended as such.

Your mentioned thoughts do not necessitate expiation unless you intended them to be included in what you vowed to abandon.

If you choose expiation, you must feed ten poor people, or clothe them, or free a slave. If you are unable to do so, then you must fast for three days.

Multiplicity in expiation is not required according to the Hanbalis, but it is required by others if you uttered a word implying repetition.